The scientists looked into how economic connections change when crossing country borders. They noticed that these links are weaker across borders because of various factors like rules and culture. Usually, studies don't consider the impact of borders when looking at these links. To tackle this, the team focused on two types of borders, within countries and crossing borders. By doing this, they found that the effects of borders are significant. They examined the average productivity of different industries in a region and linked it to how productive nearby regions are. They saw a clear difference between interactions within a country and those crossing borders. This shows that country borders really affect how economic activities spread out.